DNA Recovery from Forensically Relevant Blow Fly Larvae (Insecta, Diptera, Calliphoridae) Kept in Different Preservative Solutions.

There are still many gaps in knowledge about how different preservative solutions can guarantee sufficient DNA recovery for the taxonomic determination of flies of forensic importance. In the present study, we evaluated the recovery and amplification rates of mitochondrial DNA from larvae of the forensically important blow fly Chrysomya megacephala (F.) (Diptera, Calliphoridae), preserved for up to 47 days in the solutions commonly used in routine forensic investigations. Some larvae (N = 88) were immediately placed in the preservative solution, while another group of larvae (N = 88) was killed by immersion in water heated up to 80 °C for 30 s before being preserved at room temperature. In general, it was possible to recover highly pure DNA from larvae subjected to almost all treatments, with yields varying proportionally across different storage intervals. Among the solutions that yielded the highest DNA and consequently achieved successful amplification rates were 99.3% ethanol (> 100 ng/µL, with rates of 95%) and 70% ethanol (20-100 ng/µL, with rates of 90%), primarily up to the 28-day storage interval. The worst DNA yields and low amplification rates (approximately 50%) were associated with the 47-day storage interval, despite the preservative method used, except for Kahle's solution, which presents no amplification at all. Our results suggest that ethanol at concentrations of 70-99.3% is the most efficient preservative for preserving the integrity and usability of forensically important larvae DNA for diagnostic purposes, particularly within a range of up to 28 days.